US2502337A - Use of fluoboric acid as a means of removing core sands from castings - Google Patents
Use of fluoboric acid as a means of removing core sands from castings Download PDFInfo
- Publication number
- US2502337A US2502337A US556290A US55629044A US2502337A US 2502337 A US2502337 A US 2502337A US 556290 A US556290 A US 556290A US 55629044 A US55629044 A US 55629044A US 2502337 A US2502337 A US 2502337A
- Authority
- US
- United States
- Prior art keywords
- acid
- fluoboric acid
- castings
- fluoboric
- sand
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000002253 acid Substances 0.000 title claims description 42
- 238000005266 casting Methods 0.000 title description 15
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 7
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 230000002401 inhibitory effect Effects 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 4
- 150000007513 acids Chemical class 0.000 claims description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 17
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 15
- 239000004576 sand Substances 0.000 description 14
- 229910052742 iron Inorganic materials 0.000 description 7
- 238000005058 metal casting Methods 0.000 description 7
- 235000010338 boric acid Nutrition 0.000 description 4
- 150000001642 boronic acid derivatives Chemical class 0.000 description 4
- 229910052500 inorganic mineral Inorganic materials 0.000 description 3
- 239000011707 mineral Substances 0.000 description 3
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N Aniline Chemical compound NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 description 2
- DJHGAFSJWGLOIV-UHFFFAOYSA-N Arsenic acid Chemical compound O[As](O)(O)=O DJHGAFSJWGLOIV-UHFFFAOYSA-N 0.000 description 2
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 2
- SMWDFEZZVXVKRB-UHFFFAOYSA-N Quinoline Chemical compound N1=CC=CC2=CC=CC=C21 SMWDFEZZVXVKRB-UHFFFAOYSA-N 0.000 description 2
- DZBUGLKDJFMEHC-UHFFFAOYSA-N acridine Chemical compound C1=CC=CC2=CC3=CC=CC=C3N=C21 DZBUGLKDJFMEHC-UHFFFAOYSA-N 0.000 description 2
- 238000013019 agitation Methods 0.000 description 2
- 229940000488 arsenic acid Drugs 0.000 description 2
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 2
- 239000004327 boric acid Substances 0.000 description 2
- 125000005619 boric acid group Chemical class 0.000 description 2
- WTEOIRVLGSZEPR-UHFFFAOYSA-N boron trifluoride Chemical compound FB(F)F WTEOIRVLGSZEPR-UHFFFAOYSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 150000002222 fluorine compounds Chemical class 0.000 description 2
- 239000003112 inhibitor Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- DJHGAFSJWGLOIV-UHFFFAOYSA-K Arsenate3- Chemical class [O-][As]([O-])([O-])=O DJHGAFSJWGLOIV-UHFFFAOYSA-K 0.000 description 1
- 229910015900 BF3 Inorganic materials 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical class S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- -1 alkali metal salts Chemical class 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- GCPXMJHSNVMWNM-UHFFFAOYSA-N arsenous acid Chemical class O[As](O)O GCPXMJHSNVMWNM-UHFFFAOYSA-N 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 229910001512 metal fluoride Inorganic materials 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- HKOOXMFOFWEVGF-UHFFFAOYSA-N phenylhydrazine Chemical compound NNC1=CC=CC=C1 HKOOXMFOFWEVGF-UHFFFAOYSA-N 0.000 description 1
- 229940067157 phenylhydrazine Drugs 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D29/00—Removing castings from moulds, not restricted to casting processes covered by a single main group; Removing cores; Handling ingots
- B22D29/001—Removing cores
- B22D29/002—Removing cores by leaching, washing or dissolving
Definitions
- This invention relates to a method for removing sand from metal castings made with core sand patterns.
- Fluoboric acid can be prepared by simply mixing proper quantities of hydrofluoric and boric acids together. It may also be prepared by adding suitable fluoride and borate salts to mineral acid solution so that the fluorides and borates are converted to hydrofluoric and boric acids, respectively, which, in turn, react to form the fluoboric acid. Suitable fluorides and borates which may be used are the sodium, potassium and ammonium salts, as well as other metal fluorides and borates which are readily soluble in the mineral acid used to dissolve them. Another method for making fluoboric acid is to pass boron trifluoride gas into aqueous hydrofluoric acid.
- hydrofluoric acid In preparing hydrofluoric acid it is preferred to use reactants in such proportion that the molal ratio of fluorine to boron in the composition is not less than 4 to 1, in order to form the acid HBFi. In general, a small excess of hydrofluoric acid should be present in the fluoboric acid solution. The amount of excess hydrofluoric acid over and above the fluoboric acid should not exceed 50% by weight of the fluoboric acid present,
- Suitable corrosion inhibitors such as arsenicacid, arsenic'trioxide or soluble arsenates affd' arsenites, such as the alkali metal salts, cyanides, aniline, phenyl-hydrazine, pyridine, quinoline, acridine and mercaptans may be added in small amounts ranging from approximately 0.5% to approximately 5% by weight of the solution.
- a suitable acidagent for cleaning iron casting '5 may be prepared by adding 61.8 grams of solid boric acid to 166.8 grams of 48% aqueous hydrofluoric acid. This produces a reagent containing 38.4% by weight of fluoboric acid. To the resulting acid solution is added approximately 2% of arsenic acid.
- a solution prepared as just described will efiectively clean adhering sand particles from iron castings within a relatively short time, depending upon the amount of sand adhering to the casting. Care shouldbe exercised not to make the solution so dilute as to render it in'-' effective or only slightly effective. Solutions having a fluoboric acid content of 20% or greater may be used.
- the acid bath must be renewed from time to time as the density thereof becomes too great, or the acid content thereof becomes too low for effective use.
- the method of removing siliceous material from iron surfaces comprises bringing said material into contact with fluoboric acid.
- metal surfaces comprising immersing said surfaces in an aqueous bath containing at least 20% by weight of fluoboric acid, an amount of hydrofluoric acid less than half the amount 'of fluoboric acid and a small amount of a substance capable of inhibiting the action of the acids on the metal.
- the metal surfaces are iron and the bath contains approximately 38.4% by weight of fluoboric acid.
- the method of removing sand from metal castings which comprises contacting said castings with fluoboric acid of sufficient concentration to attack the sand in the presence of a substance capable of inhibiting the acid from attacking themetal.
- the method of removing siliceous material from metal surfaces comprising immersing said surfaces in an aqueous bath containing at least 20% by weight of fiuoboric acid and 'a small amount of hydrofluoric acid.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Mold Materials And Core Materials (AREA)
- Detergent Compositions (AREA)
Description
: g fts Patented Mar. 28, 1950 USE OF FLUOBORIC ACID AS A MEANS OF REMOVING CORE SANDS FROM CAST- INGS Harry L. Moir, Glencoe, Ill., assignor to The Pure Oil Company, Chicago, Ill., a corporation of Ohio No Drawing. Application September 28, 1944, Serial No. 556,290
This invention relates to a method for removing sand from metal castings made with core sand patterns.
In the casting of metal forms, particularly cast iron forms of intricate design using core sand patterns, it is sometimes extremely difiicult to completely remove the sand from the casting. I have discovered that residual sand which adheres to the casting can be removed by subjecting the casting to treatment with fluoboric acid containing an inhibitor to inhibit the action of the acid on the metal. Fluoboric acid dissolves silica thereby removing it from the metal casting and leaving the casting with a clean surface.
" It has already been proposed to remove sand without agitation, agitation is preferred because it speeds up the reaction. The sand grains are dissolved by the acid, and the solution so formed tends to settle toward the bottom of the treating vessel, thereby exposing the castings to fresh fluoboric acid.
Fluoboric acid can be prepared by simply mixing proper quantities of hydrofluoric and boric acids together. It may also be prepared by adding suitable fluoride and borate salts to mineral acid solution so that the fluorides and borates are converted to hydrofluoric and boric acids, respectively, which, in turn, react to form the fluoboric acid. Suitable fluorides and borates which may be used are the sodium, potassium and ammonium salts, as well as other metal fluorides and borates which are readily soluble in the mineral acid used to dissolve them. Another method for making fluoboric acid is to pass boron trifluoride gas into aqueous hydrofluoric acid.
In preparing hydrofluoric acid it is preferred to use reactants in such proportion that the molal ratio of fluorine to boron in the composition is not less than 4 to 1, in order to form the acid HBFi. In general, a small excess of hydrofluoric acid should be present in the fluoboric acid solution. The amount of excess hydrofluoric acid over and above the fluoboric acid should not exceed 50% by weight of the fluoboric acid present,
11 Claims. (Cl. 1343) and preferably not over approximately 10% by weight. Suitable corrosion inhibitors such as arsenicacid, arsenic'trioxide or soluble arsenates affd' arsenites, such as the alkali metal salts, cyanides, aniline, phenyl-hydrazine, pyridine, quinoline, acridine and mercaptans may be added in small amounts ranging from approximately 0.5% to approximately 5% by weight of the solution.
A suitable acidagent for cleaning iron casting '5 may be prepared by adding 61.8 grams of solid boric acid to 166.8 grams of 48% aqueous hydrofluoric acid. This produces a reagent containing 38.4% by weight of fluoboric acid. To the resulting acid solution is added approximately 2% of arsenic acid. A solution prepared as just described will efiectively clean adhering sand particles from iron castings within a relatively short time, depending upon the amount of sand adhering to the casting. Care shouldbe exercised not to make the solution so dilute as to render it in'-' effective or only slightly effective. Solutions having a fluoboric acid content of 20% or greater may be used.
After the sand has been completely removed from the casting itis removed from the acid bath and placed in a bath of hot water to remove the adhering acid from the casting.
The acid bath must be renewed from time to time as the density thereof becomes too great, or the acid content thereof becomes too low for effective use.
It will be seen, therefore, that I have discovered an effective method for cleaning metal castings in order to remove adhering mineral particles from portions thereof, which can be cleaned only with great difliculty by mechanical or other means.
It is claimed:
' 1. The method of removing sand from metal castings cast with sand core patterns comprising contacting said casting with fluoboric acid.
2. The method of removing siliceous material from iron surfaces comprises bringing said material into contact with fluoboric acid.
3. The method of removing siliceous material from iron surfaces comprising contacting said material with fluoboric acid containing a substance capable of inhibiting the action of the fluoboric acid on the iron.
4. The method of removing sand from iron castings comprising immersing said castings in a bath of boric and hydrofluoric acids in which hydrofluoric acid is present in excess of the amount necessary to react with boric acid to form fluoboric acid.
Bearer 5. Method in accordance with claim 4 in which the excess hydrofluoric acid is not more than approximately 10% of the fluoboric acid.
6. Method in accordance with claim 1 in which the fiuoboric acid contains a small amount of hydrofluoric acid and a material capable of inhibiting the action of the acid on the metal castings.
7. The method of removing .siliceousm'aterial...
from metal surfaces comprising immersing said surfaces in an aqueous bath containing at least 20% by weight of fluoboric acid, an amount of hydrofluoric acid less than half the amount 'of fluoboric acid and a small amount of a substance capable of inhibiting the action of the acids on the metal.
8. Method in accordance with claim '7 in which;
the metal surfaces are iron and the bath contains approximately 38.4% by weight of fluoboric acid.
9. The method of removing sand from metal castings which comprises contacting said castings with fluoboric acid of suficient concentration to attack the sand in the presence of a substance capable of inhibiting the acid from attacking themetal.
10. Method in accordance with claim 9 in which the fluoboric acid contains a small amount of hydrofluoric acid.
11. The method of removing siliceous material from metal surfaces comprising immersing said surfaces in an aqueous bath containing at least 20% by weight of fiuoboric acid and 'a small amount of hydrofluoric acid.
HARRY L. MOIR.
REFERENCES CITED The following .references are of record in the file of this patent:
UNITED STATES PATENTS
Claims (1)
- 7. THE METHOD OF REMOVING SILICEOUS MATERIAL FROM METAL SURFACES COMPRISING IMMERSING SAID SURFACES IN AN AQUEOUS BATH CONTAINING AT LEAST 20% BY WEIGHT OF FLUBORIC ACID, AN AMOUNT OF HYDROFLUORIC ACID LESS THAN HALF THE AMOUNT OF FLUOBORIC ACID AND A SMALL AMOUNT OF A SUBSTANCE CAPABLE OF INHIBITING THE ACTION OF THE ACIDS ON THE METAL.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US556290A US2502337A (en) | 1944-09-28 | 1944-09-28 | Use of fluoboric acid as a means of removing core sands from castings |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US556290A US2502337A (en) | 1944-09-28 | 1944-09-28 | Use of fluoboric acid as a means of removing core sands from castings |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2502337A true US2502337A (en) | 1950-03-28 |
Family
ID=24220714
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US556290A Expired - Lifetime US2502337A (en) | 1944-09-28 | 1944-09-28 | Use of fluoboric acid as a means of removing core sands from castings |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2502337A (en) |
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2609576A (en) * | 1949-12-06 | 1952-09-09 | Thompson Prod Inc | Method of making hollow shapes |
| US2687278A (en) * | 1948-05-26 | 1954-08-24 | Chrysler Corp | Article with passages |
| US2695433A (en) * | 1953-10-08 | 1954-11-30 | Ames Howard Wesley | Dental stress breaker former |
| DE1033480B (en) * | 1952-11-07 | 1958-07-03 | Walter Eckhoff Dipl Ing | Pickling solution for pickling iron sheets from the enamelling |
| US2986499A (en) * | 1958-01-17 | 1961-05-30 | Du Pont | Electropolishing steel |
| US3033795A (en) * | 1957-06-10 | 1962-05-08 | Purex Corp Ltd | Compositions and process for removal of radioactive contaminants |
| US3181984A (en) * | 1962-05-04 | 1965-05-04 | Fmc Corp | Cleaning and brightening of solder |
| US3617747A (en) * | 1968-09-26 | 1971-11-02 | Gen Electric | Detecting minute amounts of residual core material by means of neutron radiography |
| US3727670A (en) * | 1971-05-27 | 1973-04-17 | American Lava Corp | Leachable ceramic cores |
| US4076779A (en) * | 1975-08-01 | 1978-02-28 | Wallace-Murray Corporation | Method of restoring the fluid permeability of a used, ceramic fluid-release mold |
| US4540467A (en) * | 1974-01-02 | 1985-09-10 | Grube Kenneth E | Method for fragmenting municipal solid wastes |
| US4804422A (en) * | 1986-02-06 | 1989-02-14 | U.S. Philips Corporation | Method of purifying quartz sand |
| US5536484A (en) * | 1994-10-11 | 1996-07-16 | Elf Atochem S.A. | Production of aqueous solutions of fluoboric acid |
| US7182121B1 (en) | 2004-06-28 | 2007-02-27 | Viel David W | Investment casting method and materials |
| CN105945262A (en) * | 2016-05-09 | 2016-09-21 | 广东富行洗涤剂科技有限公司 | Acidic shell mold removing agent |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1011203A (en) * | 1910-06-16 | 1911-12-12 | Mix & Genest Telephon Und Telegraphen Werke Ag | Process for pickling aluminium and its alloys prior to galvanizing or coating the same with other metals. |
| US1279331A (en) * | 1918-05-11 | 1918-09-17 | James H Gravell | Pickling iron and steel. |
| US1877504A (en) * | 1932-06-30 | 1932-09-13 | Dow Chemical Co | Treatment of deep wells |
| US2011579A (en) * | 1933-04-21 | 1935-08-20 | Dow Chemical Co | Intensified hydrochloric acid |
| GB463545A (en) * | 1935-08-26 | 1937-03-30 | Du Pont | Improvements in or relating to the production of boron compounds and their use as catalysts |
| GB473556A (en) * | 1935-04-13 | 1937-10-14 | Ig Farbenindustrie Ag | Improvements in or relating to methods and agents for removing enamel from enameled articles |
| US2362875A (en) * | 1943-06-03 | 1944-11-14 | Austenal Lab Inc | Casting procedure |
| US2414326A (en) * | 1944-01-19 | 1947-01-14 | Aluminum Co Of America | Cleaning filter cloth |
-
1944
- 1944-09-28 US US556290A patent/US2502337A/en not_active Expired - Lifetime
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1011203A (en) * | 1910-06-16 | 1911-12-12 | Mix & Genest Telephon Und Telegraphen Werke Ag | Process for pickling aluminium and its alloys prior to galvanizing or coating the same with other metals. |
| US1279331A (en) * | 1918-05-11 | 1918-09-17 | James H Gravell | Pickling iron and steel. |
| US1877504A (en) * | 1932-06-30 | 1932-09-13 | Dow Chemical Co | Treatment of deep wells |
| US2011579A (en) * | 1933-04-21 | 1935-08-20 | Dow Chemical Co | Intensified hydrochloric acid |
| GB473556A (en) * | 1935-04-13 | 1937-10-14 | Ig Farbenindustrie Ag | Improvements in or relating to methods and agents for removing enamel from enameled articles |
| GB463545A (en) * | 1935-08-26 | 1937-03-30 | Du Pont | Improvements in or relating to the production of boron compounds and their use as catalysts |
| US2362875A (en) * | 1943-06-03 | 1944-11-14 | Austenal Lab Inc | Casting procedure |
| US2414326A (en) * | 1944-01-19 | 1947-01-14 | Aluminum Co Of America | Cleaning filter cloth |
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2687278A (en) * | 1948-05-26 | 1954-08-24 | Chrysler Corp | Article with passages |
| US2609576A (en) * | 1949-12-06 | 1952-09-09 | Thompson Prod Inc | Method of making hollow shapes |
| DE1033480B (en) * | 1952-11-07 | 1958-07-03 | Walter Eckhoff Dipl Ing | Pickling solution for pickling iron sheets from the enamelling |
| US2695433A (en) * | 1953-10-08 | 1954-11-30 | Ames Howard Wesley | Dental stress breaker former |
| US3033795A (en) * | 1957-06-10 | 1962-05-08 | Purex Corp Ltd | Compositions and process for removal of radioactive contaminants |
| US2986499A (en) * | 1958-01-17 | 1961-05-30 | Du Pont | Electropolishing steel |
| US3181984A (en) * | 1962-05-04 | 1965-05-04 | Fmc Corp | Cleaning and brightening of solder |
| US3617747A (en) * | 1968-09-26 | 1971-11-02 | Gen Electric | Detecting minute amounts of residual core material by means of neutron radiography |
| US3727670A (en) * | 1971-05-27 | 1973-04-17 | American Lava Corp | Leachable ceramic cores |
| US4540467A (en) * | 1974-01-02 | 1985-09-10 | Grube Kenneth E | Method for fragmenting municipal solid wastes |
| US4076779A (en) * | 1975-08-01 | 1978-02-28 | Wallace-Murray Corporation | Method of restoring the fluid permeability of a used, ceramic fluid-release mold |
| US4804422A (en) * | 1986-02-06 | 1989-02-14 | U.S. Philips Corporation | Method of purifying quartz sand |
| US5536484A (en) * | 1994-10-11 | 1996-07-16 | Elf Atochem S.A. | Production of aqueous solutions of fluoboric acid |
| US7182121B1 (en) | 2004-06-28 | 2007-02-27 | Viel David W | Investment casting method and materials |
| CN105945262A (en) * | 2016-05-09 | 2016-09-21 | 广东富行洗涤剂科技有限公司 | Acidic shell mold removing agent |
| CN105945262B (en) * | 2016-05-09 | 2018-12-04 | 广东富行洗涤剂科技有限公司 | It is a kind of acid except shell mold agent |
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